Pool Volume Calculator

Knowing your pool's exact volume is essential for maintaining proper water chemistry — chlorine, shock, algaecide, and pH adjuster dosages are all calculated per gallon (or per 10,000 gallons) of pool water. It's also useful for sizing a pool heater or pump, estimating fill time and water cost, and planning a pool cover or liner.

This calculator supports the four most common residential pool shapes — rectangular, round, oval, and kidney-shaped — and lets you enter either a single average depth or separate shallow and deep-end depths for pools with a sloped floor, which is typical of most in-ground pools.

Nearly every pool chemical product — chlorine tablets, liquid shock, algaecide, stabilizer, pH increaser/decreaser — lists its dosage per a specific volume of water, usually per 10,000 gallons. Using the wrong pool volume when dosing chemicals is one of the most common causes of cloudy water, algae blooms, or over-chlorination that can irritate skin and eyes and damage pool equipment.

Once you know your pool's volume in gallons, most product labels make it easy to scale the recommended dose — for example, a product calling for "1 lb per 10,000 gallons" for a 20,000-gallon pool means using 2 lbs.

For the most accurate volume estimate:

• Measure length and width at the widest points of the pool (for round pools, measure the diameter through the center).
• For sloped floors, measure the true shallow-end and deep-end depths rather than guessing — many pools have a shallow end around 3–4 feet and a deep end of 7–9 feet.
• For kidney and free-form pools, measure the two longest length dimensions and the widest width point; the built-in approximation accounts for the curved, non-rectangular shape.
• Measure to the waterline, not the top of the pool wall, for the most accurate depth reading.